The percentage % of modulation is an indicator of the extent to which it is modulated.
Here is a picture of an unmodulated sine wave.
![](https://i0.wp.com/www.onesdr.com/wp-content/uploads/2022/09/unmodulated-sine.png?w=770&ssl=1)
By comparison here is a picture of an Amplitude Modulated sine wave.
![](https://i0.wp.com/www.onesdr.com/wp-content/uploads/2022/09/vmax-vmin-AM-1024x576.jpg?resize=770%2C433&ssl=1)
Formula
The percent modulation is given by
%M = ((VMAX-VMIN)/(VMAX+VMIN)) * 100
Calculator
Example
In the following example, VMAX = 2.5, VMIN = -0.5. Using these numbers in the calculator gives 150% modulation. This is an example of an overmodulated signal.
![](https://i0.wp.com/www.onesdr.com/wp-content/uploads/2022/09/Modulation-Percent-150.png?w=770&ssl=1)
If VMAX = VMIN, the sine wave is not modulated and the percentage modulation is 0.